|For an overview of this weapon, see Fat Man.|
First entering service in September 2077 with the U.S. Army, the Fat Man is a shoulder-mounted mini nuke launcher. The variant appearing in Fallout 4 has a slightly different appearance than in previous games. There is no longer a handle on the right side of the launcher, and instead two straight handles on the bottom. It also appears to be larger, with a rusted silver paint job.
Developers struggled to find a way to fire the heavy ammunition from a man-portable system far enough to keep the operator outside the blast radius, losing a lot of people in the process. Eventually, it was discovered that by placing a small sub-charge into the ammunition itself, similar to bullets being fired from a gun (or perhaps more accurately described as being along the lines of a recoilless launcher), the warheads could be launched a considerable distance without adding too much weight to the already heavy weapon.
When fitted with the MIRV launcher, it fires six mini nukes in a cluster that separates in mid-air, drastically reducing its range, but increasing its overall damage and area of effect.
- Big Boy, a unique version with the Two Shot legendary modification.
- The Striker, a unique version that fires modified bowling balls instead of mini nukes.
- Nuka-nuke launcher, a unique version that deals 50% more damage than the standard model by firing quantum-enhanced Nuka-nukes.
- ArcJet Systems - Found in the room marked '2' in the Engine core.
- BADTFL regional office - In the evidence locker.
- Boston Airport - Slightly north of Boston Airport, there are wrecked cars. Inside one is a Fat Man. From the Boston Airport fast travel location, head east. The Fat Man is located in a van on the water's edge behind the nose section of an airplane.
- Boston mayoral shelter - Beneath the basketball court is an entrance to a cave. The Fat Man lies next to a dead soldier at the end of the cave. There is a nearby deathclaw that will attack on sight.
- Cabot House - In the basement near Edward's bed.
- D.B. Technical High School - At the far end of the old swimming pool in the northwest corner of the lowest level of the school. This is by the raider boss' bed and terminal.
- Federal ration stockpile - In the main stockpile area, just inside the room with two turrets against the wall near the terminal that operates the doors (the second one). This Fat Man also respawns.
- Fort Hagen - In the armory.
- Goodneighbor - Found behind the desk, beside KL-E-0 in the Kill or Be Killed store.
- Gunners plaza - In a locked utility closet in the southwest corner of the second floor.
- Hub City Auto Wreckers - Carried by a named Gunner, Bridget.
- Lexington - On the walkway where the raider with the power armor is found.
- Libertalia - Carried by a random raider at the top of the main building.
- Malden center - Found behind a train car hugging a wall.
- Outpost Zimonja - Carried by a raider in power armor named Boomer.
- Quincy ruins - Being held by Sergeant Baker, who is located on top of the church in the ruins.
- Revere satellite array - Can be found at the top of one of the towers, next to a power armor frame and a case with miscellaneous ammo and other items.
- Robotics disposal ground - Found laid on top of a car hood near the back of the scrapyard.
- Salem - On a shelf in a bombed-out store across from the chapel.
- Spectacle Island - On the lower level of the beached tugboat containing the generator.
- The Castle - Found in the armory on a shelf, next to it will be a mini nuke.
- The Prydwen - Inside Proctor Teagan's store.
- Zephyr Ridge Camp - Carried by a Trapper on the tower's top level.
- There is a chance that a mini nuke fired by the Fat Man will be a dud and cause physical damage instead to the target if hit by the dud.
- Technical documentation and holotapes found in Fort Strong reveals the Fat Man's pre-War designation: "The M42 Fat Man."
- When fired from a long enough distance, the projectile makes a loud whistling noise (similar to the cartoon noise for falling from the sky or the sound that bombs make after being dropped) which indicates one should get to cover.
- When firing with the experimental MIRV modification, there is a chance that it will detonate right at one's feet, even if they are firing away from themselves.
- During the first scene of the game, the player character can see an advertisement for the Fat Man playing on TV.
- This same advertisement for the Fat Man was a promotional advertisement for Fallout 3.
- Despite Elder Maxson stating that the Fat Man is an essential part of the Brotherhood arsenal, BOS soldiers never use them.
- When displaying damage on a target's health bar, only the physical impact damage is displayed.
- In survival mode, mini nukes weigh in at 12 units each in addition to the Fat Man's 30+.
Behind the scenes
"Fat Man" is the codename for the type of nuclear bomb that was detonated over the Japanese city of Nagasaki by the United States on 9 August 1945.
- General Brock's terminal in Fort Strong and Private Murnahan's holotape found in Fort Strong refer to the Fat Man as an "M42 nuclear catapult"
- Ten things we've learned about Fallout 4 - Tech Radar (dead link)